[Stoves] TLUD pellets stove with a venturi burner (only works for wood pellets)

alex english aenglish444 at gmail.com
Sun Oct 11 12:02:05 CDT 2015


Roberto,
I like what you have done. A stable blue flame is interesting. Do you think
you are getting a bit of premix happening with you lowest secondary holes?
I have two theories about the colour. One is a combination of premix and
excess air. The other is that at low turn down, low superficial velocities,
you get peak bed temperatures down around 500C or even lower at the sides
of the chamber or maybe even inside the pellet. I think there might be a
different mix of gasses at these temperatures that make it easier to burn
without forming soot that turns the flame yellow/orange. Perhaps a lower
C/H ratio.
When I add a logs to a bed of coals in my stove, with the primary air shut,
I see dancing blue flames for quite a while before they turn yellow.

I had a choked exit on some of my TLUD burners, cone in to secondary air
and cone out. I called them venturi burners because of the look but I
abandoned the name because I felt it was all chimney-effect.  I'd like to
see you have control of the secondary air on the cylinder portion.

If you get a combustion test done, don't be surprised if the best result is
with a flame with yellow tips.

Nice work.
Alex

On Sat, Oct 10, 2015 at 10:58 PM, Roberto Poehlmann <
roberto.poehlmann at gmail.com> wrote:

> Hi to all,
> About the venturi burner (tube and cone) after the concentrator ring, i
> forget to say that this burner only works for wood pellets.
> I found that with wood sticks, wood chips or hard shells the burner does
> not works.
> The velocity of the gases and secondary air is more than the flame speed.
>
> The reason, i think, is that for the same amount of primary air, the
> amount of pyrolysis gases is more with pellets than with wood chips for
> example. So, with the others combustibles, they needs more primary air
> velocity to produce the same amount of pyrolysis gases.
>
> But, if you go to the opposite direction, you can obtain more smoke with
> the same amount of primary air. So, i will try with 6mm pellets with
> shorter length (very short length) to see what happens.
>
> This is the reason that 10 mm pellets lasts longer than 6 mm pellets (as
> it is seen in a previous video in vimeo site)
>
> Greetings
> Roberto Poehlmann
>
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